Print Preview: Display a throbber when the user requests the system print

chrome/common/print_messages.h

Index: chrome/common/print_messages.h
diff --git a/chrome/common/print_messages.h b/chrome/common/print_messages.h
index 44de3e24d068969bd48fb4c449eecf0db4b47558..cb29ad1cddd2b3b555bbd6d6134817a340e38dd7 100644
--- a/chrome/common/print_messages.h
+++ b/chrome/common/print_messages.h
@@ -178,6 +178,9 @@ IPC_MESSAGE_ROUTED2(PrintHostMsg_DidGetPrintedPagesCount,
                     int /* rendered document cookie */,
                     int /* number of rendered pages */)
 
+// Tells the browser that the print dialog has been shown.
+IPC_MESSAGE_ROUTED0(PrintHostMsg_DidShowPrintDialog)
+
 // Sends back to the browser the rendered "printed page" that was requested by
 // a ViewMsg_PrintPage message or from scripted printing. The memory handle in
 // this message is already valid in the browser process.